Additives for mineral building materials containing cement

ABSTRACT

Mixtures of at least one polycarboxylate-based plasticizer for cement-comprising mineral building materials, and butoxylated polyalkylenepolyamines or their salts as air detrainers, and the use of such mixtures as additives for mineral building materials comprising cement, are described.

The invention relates to mixtures of at least one air detrainer and atleast one polycarboxylate-based plasticizer for mineral buildingmaterials which comprise cement, and to the use of aqueous solutions ofsuch mixtures as additives for mineral building materials comprisingcement.

WO-A-83/02938 discloses hydraulic cement mixtures which compriseethoxylated or propoxylated polyamines or polyethylenimines for strengthenhancement. DE-A-44 20 444 discloses additives for cement-comprisingcompositions. They include at least one cement plasticizer and at leastone antifoam. Examples of appropriate plasticizers are aqueous solutionsof copolymers containing, in copolymerized form, monoethylenicallyunsaturated carboxylic acids and polyalkylene glycol esters of acrylicor methacrylic acid. The plasticizers are used in combination with anantifoam which is either dissolved in the polymer solution or dispersedtherein in particles having a diameter of not more than 20 μm. Examplesof the antifoams are adducts of ethylene oxide and/or propylene oxidewith alcohols or phenols. Insofar as such mixtures are not clear aqueoussolutions, additives of this kind lack sufficient stability on storageand separate into two phases.

DE-A-19653524 discloses copolymers of ethylenically unsaturatedcarboxylic acids and polyalkylene glycol esters of acrylic ormethacrylic acid that are obtainable by polymerizing the monomers in thepresence of compounds comprising phosphorus in bonded form. Suchcopolymers are highly effective plasticizers for cement mixtures such asconcrete or mortar. They are used in amounts of, for example, from 0.01to 10% by weight, preferably from 0.05 to 3% by weight, based on theweight of the cement. Advantageously, the plasticizers are used inconjunction with antifoams in order to reduce the level of air pores.Examples of air detrainers suitable for achieving reduction in air poresare products based on polyalkylene oxides, such as adducts of ethyleneoxide or propylene oxide with alcohols or phenols; phosphates such astributyl phosphate or triisobutyl phosphate, phthalates such as dibutylphthalate, siloxanes such as polydimethylsiloxane, or phosphates ofethoxylated fatty alcohols, such as ethylene oxide stearyl phosphate.Air detrainers of this kind are customarily employed in amounts from0.05 to 10% by weight, preferably from 0.5 to 5% by weight, based on thepolymers that are used as plasticizers.

Further plasticizers used for mineral building materials arehomopolymers and copolymers of ethylenically unsaturated carboxylicacids and dicarboxylic acids with styrene (EP-A-0 306 449) or isobuteneor diisobutene (EP-A-0 338 293, U.S. Pat. No. 4,586,960 and U.S. Pat.No. 4,906,298). When polycarboxylate-based plasticizers are incorporatedinto mineral building materials considerable amounts of air areintroduced. As a result of the air pores, voids are formed in theconcrete, leading to a significant deterioration in the mechanicalproperties and stability of the concrete. To reduce the level of airpores in the concrete when using plasticizers, it is usual to employ theplasticizers together with air detrainers. Mixtures ofpolycarboxylate-based plasticizers with air detrainers of the typedescribed above, however, are not sufficiently stable on storage.

It is an object of the present invention to provide storage-stablemixtures of at least one air detrainer and a polycarboxylate-basedplasticizer for mineral building materials comprising cement.

We have found that this object is achieved, in accordance with theinvention, by mixtures of at least one air detrainer and at least onepolycarboxylate-based plasticizer for mineral building materialscomprising cement if said mixtures comprise butoxylatedpolyalkylenepolyamines or their salts as air detrainers. Particularpreference is given to mixtures comprising water-soluble butoxylatedpolyethylenimines as air detrainers.

By mineral building materials are meant preparations comprising asessential constituents mineral binders such as lime and/or, inparticular, cement and also—as aggregates—sands, gravels, crushed rocksor other fillers, such as natural or synthetic fibers. The mineralbuilding materials are generally converted, by commixing the mineralbinders such as cement and the aggregates together with water, into aready-to-use formulation which hardens both in air and under water to astonelike material. So that the cement-comprising mineral buildingmaterials have favorable service properties—i.e., are pumpable—whilekeeping the ratio of water to cement as low as possible, use is made,for example, of polycarboxylates, which are described in the abovereferences. Examples of suitable polycarboxylates are homopolymers andcopolymers of acrylic or methacrylic acid, copolymers of styrene andmaleic anhydride, copolymers of isobutene and maleic anhydride, andcopolymers of diisobutene and maleic anhydride. Particularly preferredplasticizers for cement-comprising mineral building materials are, forexample, polyalkylene glycol-acrylic and/or methacrylic acid copolymersesterified with one mole of acrylic or methacrylic acid. Such copolymersare disclosed, for instance, in the cited prior art documents DE-A4420444 and DE-A 19653524.

Since the use of polycarboxylates alone as plasticizers forcement-comprising mineral building materials is accompanied by arelatively sharp increase in the air pore content of said materials, theinvention involves using the customary plasticizers in conjunction withbutoxylated polyalkylenepolyamines or their salts in order to reduce theair pore content of mineral building materials. Examples of thepolyalkylenepolyamines to be butoxylated are diethylenetriamine,triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine,3-(2-aminoethyl)aminopropylamine, 2-(diethylamino)ethylamine,3-(dimethylamino)propylamine, dimethyldipropylenetriamine,4-aminoethyl-1,8-octanediamine, 3-(diethylamino)propylamine,N,N-diethyl-1,4-pentanediamine, dipropylenetriamine,bis(hexamethylene)triamine, N,N-bis(aminopropyl)methylamine,N,N-bis(aminopropyl)ethylamine, N,N-bis(aminopropyl)hexylamine,N,N-bis(aminopropyl)octylamine, N,N-dimethyldipropylenetriamine,N,N-bis(3-dimethylaminopropyl)amine, N-(aminoethyl)butylenediamine,N-(aminopropyl)butylenediamine, bis(aminopropyl)butylenediamine, andpolyethylenimines. The polyethylenimines have molecular masses, forexample, of from 200 to 5000, preferably from 400 to 3000. Withparticular preference, polyethylenimines having molecular masses from600 to 2000 are used for the butoxylation.

The butoxylated polyalkylenepolyamines contain, for example, from 0.1 to10 mol of butylene oxide added on per nitrogen group. Preference isgiven to the use of air detrainers obtainable by butoxylatingpolyethylenimines having molecular masses from 200 to 5000 with from 0.1to 10 mol of butylene oxide per mole of ethylenimine units in thepolyethylenimine. Air detrainers used with particular preference are thereaction products obtainable by butoxylating polyethylenimines havingmolecular masses from 400 to 3000 with from 0.3 to 5 mol of butyleneoxide per mole of ethenimine units in the polyethylenimine. The bestresults in terms of air detrainment are obtained with reaction productsobtainable by butoxylating polyethylenimines having molecular massesfrom 600 to 2000 with from 0.8 to 2 mol of butylene oxide per mole ofethylenimine units in the polyethylenimine.

The reaction products of butylene oxide with polyalkylenepolyamines canbe used directly in the form as obtained from the butoxylation or elsein the form of a salt with, for example, mineral or organic acids suchas carboxylic acids or sulfonic acids. The polyalkylenepolyamines can bebutoxylated in either one or two stages. In the one-stage procedure, forexample, the polyalkylenepolyamines are charged to a reactor togetherwith an alkaline catalyst and the required amount of butylene oxide isinjected. The reaction temperature can be, for example, from 25 to 150°C. In the case of multistage addition of butylene oxide the procedureis, for example, in the first stage to charge an aqueous solution of apolyalkylenepolyamine to a pressure vessel fitted with a stirrer and tosubject this initial charge at a temperature of 25 to 150° C. to theaction of sufficient butylene oxide that primary and secondary aminogroups are converted to aminobutanol groups. In the second stage of thebutylene oxide addition first the water is removed, an organic solventis introduced, if desired, and then, in the presence of an alkalinecatalyst, butylene oxide is added on to the reaction product obtained inthe first stage. Examples of catalysts used are sodium methoxide,potassium tert-butoxide, potassium hydroxide, sodium hydroxide, sodiumhydride, potassium hydride, and basic ion exchangers. Subsequentbutoxylation of the product obtained in the first stage takes place atfrom 25 to 150° C. Butoxylation can be effected using 1,2-butyleneoxide, 2,3-butylene oxide, or mixtures of said butylene oxides. It ispreferred to use 1,2-butylene oxide.

The butoxylated polyalkylenepolyamines may be dissolved in water. Wheretheir solubility in water in their free base form is poor ornonexistent, a mineral or organic acid, such as a carboxylic or sulfonicacid, is added. The resultant salts of butoxylatedpolyalkylenepolyamines are readily soluble in water. Salt formation maybe partial—from 5 to 50% by weight, for example, preferably from 10 to30% by weight—or else full. It is possible, for example, to prepareaqueous solutions of butoxylated polyalkylenepolyamines whoseconcentration of butoxylation products is from 10 to 90% by weight,preferably from 50 to 70% by weight. Salts can be formed using, forexample, mineral acids such as hydrochloric acid, sulfuric acid orphosphoric acid, or carboxylic acids. Examples of suitable carboxylicacids are formic, acetic and propionic acid. Further suitable organicacids are, for example, toluenesulfonic acid, benzenesulfonic acid, andalkylsulfonic acids such as methanesulfonic acid. To form water-solublesalts of butoxylated polyalkylenepolyamines it is preferred to useacetic acid.

The butoxylated polyalkylenepolyamines can be added in free base or saltform to a mineral building material comprising a polycarboxylate-basedplasticizer. For each 100 parts by weight of a polycarboxylate-basedplasticizer in the mineral building material use is made of from 0.3 to30 parts, preferably from 0.3 to 3 parts, by weight of a butoxylatedpolyalkylenepolyamine or salt thereof in order to reduce the air porecontent in the concrete.

In order to establish the desired service properties of theready-to-use, cement-comprising mineral building materials, preferenceis given to the use of an aqueous solution of mixtures of apolycarboxylate and water-soluble butoxylated polyalkylenepolyamines.The invention therefore also provides aqueous solutions of mixtures of

(a) a water-soluble copolymer containing from 98 to 2% by weight ofunits of esters of formula (I)

in which R¹ and R² are identical or different and are H or CH₃, A is analkylene group with 2 to 4 carbon atoms, R³ is H or C₁-C₂₂-alkyl, and nis from 1 to 300, and from 2 to 98% by weight of units of acrylic acid,methacrylic acid, their alkali metal salts and ammonium salts, andmixtures thereof, and

(b) water-soluble butoxylated polyalkylenepolyamines, said mixturescontaining from 0.3 to 30 parts by weight of component (b) per 100 partsby weight of component (a) and the concentration of component (a) in theaqueous solution being from 5 to 80% by weight.

Particular preference is given to plasticizers where the water-solublecopolymer contains from 5 to 50 and, in particular, from 15 to 30alkylene oxide units. Examples of suitable alkylene oxides are ethyleneoxide, propylene oxide and butylene oxides, preference being given tothe use of ethylene oxide. Alternatively, random polymers or blockcopolymers of ethylene oxide and propylene oxide or of ethylene oxide,propylene oxide and butylene oxide can be used to prepare the esters ofthe formula (I). Apart from in the prior art references cited above,copolymers suitable as plasticizers for cement-comprising mineralbuilding materials are described in EP-A 0 753 488, EP-A 734 359, andJP-A-58/74552. Particularly preferred plasticizers are prepared, forexample, by free-radical copolymerization of from 60 to 90% by weight ofat least one compound of the formula (I) above and from 10 to 40% byweight of acrylic acid, methacrylic acid or mixtures thereof, the sum ofthe percentages by weight being in each case 100, in aqueous solution.Of particular advantage in this context are copolymers prepared in thepresence of from 0.01 to 50% by weight, based on the monomers to bepolymerized, of compounds containing phosphorus in bonded form. Examplesof suitable compounds of this type are phosphinic acid, hypophosphorousacid, phosphonic acid, phosphorous acid, and the salts of these acids.The molecular mass of the polymers to be used as plasticizers lies, forexample, within the range from 10,000 to 500,000.

In order to reduce the air pores in concrete, the above-describedmixtures of an air detrainer and a plasticizer based on a water-solublecopolymer preferably comprise water-soluble butoxylatedpolyethylenimines or their salts. As component (b) of the aqueousmixtures it is preferred to use the reaction products obtainable bybutoxylating polyethylenimines having molecular masses from 200 to 5000with from 0.1 to 10 mol of butylene oxide per mole of ethylenimine unitsin the polyethylenimine, or salts of said reaction products.Particularly advantageous as component (b) of the aqueous mixtures arereaction products obtainable by butoxylating polyethylenimines havingmolecular masses from 400 to 3000 with from 0.3 to 5 mol of butyleneoxide per mole of ethylenimine units in the polyethylenimine, or saltsof said reaction products. For the majority of practical applications,use is made of aqueous mixtures in which the air detrainers used toreduce the air pores in concrete comprise reaction products obtainableby butoxylating polyethylenimines having molecular masses from 600 to2000 with from 0.8 to 2 mol of butylene oxide per mole of ethylenimineunits in the polyethylenimine, or salts of said reaction products. Themixtures described above are used as additives for mineral buildingmaterials comprising cement. In this utility, based on cement, forexample, from 0.01 to 10% by weight, preferably from 0.05 to 3% byweight, is used of a mixture of the above-described components (a) and(b), with the mixtures of components (a) and (b) preferably beingemployed in the form of an aqueous solution. The pH of the aqueoussolutions of such mixtures is, for example, from 6 to 12, and preferablybelow 10. Although the above-described mixtures of a polycarboxylate andat least one butoxylated polyalkylenepolyamine or salts thereof aremostly employed in the form of aqueous solutions containing (indissolved form), for example, from 5 to 80 percent by weight ofplasticizer and air detrainer they can also be added in finely dividedanhydrous form, for example, as powders or granules, to cement, gypsumor lime as an additive for producing mineral building materials.Particular preference is given to pulverulent mixtures of cement and acombination of plasticizer and air detrainer in which the cementcomprises from 0.01 to 10% by weight of the pulverulent combination ofplasticizer and air detrainer in extremely uniform distribution.

Unless evident otherwise from the context, the percentages in theexamples are in each case by weight, as are the parts.

Determining the Average Molecular Weight

The weight-average molecular weight was determined by gel permeationchromatography (GPC) using aqueous eluents. Calibration was conductedwith a Na polyacrylate standard of narrow distribution. The eluent usedwas an aqueous solution of potassium dihydrogen phosphate and sodiumchloride. The internal standard used was polyethylene glycol. Thechromatography columns were packed with TSK PW-XL 3000 and TSK PW-XL5000 (from TosoHaas) as stationary phase. Detection was made with adifferential refractometer.

Determining the K Value

The K values of the aqueous sodium salt solutions of the copolymers weredetermined in accordance with H. Fikentscher, Cellulose-Chemie 13,(1932) 58-64 and 71-74 in aqueous solution at a pH of 7, a temperatureof 25° C., and a copolymer sodium salt concentration of 1% by weight.

Determining the Solids Content

A defined amount of the sample (about 0.5-1 g) is weighed into analuminum boat (initial weight). The sample is dried under an IR lamp(160 volts) for 30 minutes. Then the mass of the sample is measuredagain (final weight). The percentage solids content SC is calculated asfollows:

SC=final weight×100/initial weight [% by wt.]

Performance Tests

Test procedure for concrete plasticizers, on the basis of DIN 1048 Part1 (Testing the plasticizing action of additives in concrete)

Apparatus:

MultiFlow stirrer type SE/GB (electric motor)

Stirred vessel (h=20.7 cm ; d=40.6 cm)

Slump base (700 mm×700 mm with movable top plate; see DIN 1048 Part 1,3.2.1.1)

Truncated cone mold (internal diameter top: 130 mm; internal diameterbottom: 200 mm; see DIN 1048 Part 1, 3.2.1.1)

Air pore content measuring instrument (see DIN 1048 Part 1, 3.5.1);sample container (h=8.3 cm ; d=12.3 cm) with screw-on pressure meter

Shaker table (electrical)

Stopwatch

Wooden rod (d=1.5 cm ; 1=55 cm)

Hand scoop (capacity about 0.6L)

Plastic cube mold (inner edge length L*W*H=15 cm*15 cm*15 cm; open onone side)

Materials:

Mix: Mixing ratio cement/aggregate 1:5.56, grading curve B 16

Quartz sand F34 825 g Quartz sand 0.15-0.6 mm 1665 g Quartz sand0.5-1.25 mm 2715 g Quartz sand 1.5-3.0 mm 1485 g Gravel 3-8 mm 3765 gGravel 8-16 mm 3330 g Heidelberger Zement 2475 g CEM I 32.5R Tap water1081 g

Plasticizer as per Table 1 (% of plasticizer, based on solid polymer peramount of cement used; “solids/solids”)

Notes:

The amount of water added with the plasticizer must be subtracted fromthe tap water component. The water/cement ratio is 0.45. The quality ofthe cement used is checked by sifting.

Test Procedure:

a. Preparing the concrete:

All of the aggregates are weighed into the stirred vessel and mixed dryfor 1 minute with the MultiFlow stirrer. Two thirds of the calculatedamount of water is then added within a period of 30 seconds, whilestirring. Over the next 30 seconds the remaining third of water, admixedwith plasticizer, is added to the mixture. The concrete is then stirredfor a further 3 minutes. After a total of 5 minutes the preparation ofthe concrete mixture is at an end. After the concrete has been prepared,the first slump measurement is taken.

b. Slump test:

After the finished concrete composition has been stirred for 5 minutesthe first slump measurement is made (see DIN 1048 Part 1, 3.2.1.2Procedure for testing slump). After the slump has been determined theconcrete is returned from the slump base back into the stirred vessel.After a total of 29 minutes 45 seconds the concrete is mixed again for15 seconds. The second measurement is carried out after exactly 30minutes. This procedure is repeated after total elapsed times of 60, 90and 120 minutes or until the measured slump has been reduced to a spreaddiameter of less than 30 cm.

c. Air pore content:

The air content of fresh concrete is measured by the pressureequilibration method using a calibrated test apparatus having a capacityof 11. The air pore content is measured after the first and last slumpmeasurement, respectively. Measurement is made by filling the vessel ofthe air pore content measuring instrument with concrete while theconcrete is being compacted for 60 seconds on a shaker table. Aftershaking, the vessel must be full to the brim with concrete (forprocedure see DIN 1048 Part 1, 3.5 Air content). Measurement of the airpore content is then carried out.

d. Testing compressive strength:

Because of the effect of the tested concrete plasticizers on the settingcapability of the concrete, a compressive strength test is carried outwhen required. The compressive strength is determined on test specimensproduced in house with an edge length of 15 cm*15 cm*15 cm. At least twocubes are produced from the concrete mixture. The test specimens areproduced by half-filling the cubes with concrete, compacting theconcrete for 20 seconds on the shaker table, and then adding sufficientconcrete to the cube mold that following further compaction for 20seconds the surface of the concrete is higher than the edge of theactual mold. Finally, the surface of the test specimens is leveled so asto be flush with the height of the cube mold. For the compressivestrength test the specimens are stored in a closed room at about 23° C.They should be set down initially in their molds and covered to protectagainst moisture loss. After about 18 hours the cubes are removed fromthe molds, and after 24 hours from the time when the concrete mixturewas prepared a cube is tested using a press. The force value attained,in kN, is reported in N/mm² and indicates the strength of the concreteafter 24 hours. Following storage of the second concrete cube for 28days from the time of preparation of the concrete, the same testprocedure is repeated on the remaining test specimen to determine thecompressive strength after 28 days.

Notes:

Before each new series of tests a test without added plasticizer (blankvalue) must be conducted. Care must also be taken to ensure that theambient temperature is constant (23-25° C.).

Preparing the Air Detrainers

Air Detrainer 1

A heatable autoclave provided with a stirrer was charged under nitrogenwith 43 g of polyethylenimine of average molecular mass M_(w) 1300 inthe form of a 50% strength aqueous solution. The autoclave was closedand the reactor contents were heated with stirring to a temperature of90° C. As soon as this temperature was reached 72 g of 1,2-butyleneoxide were injected and the reaction mixture was stirred to constantpressure. The contents of the autoclave were then cooled to 70° C. Thewater in the resultant reaction mixture was removed by distillation in arotary evaporator under reduced pressure. This gave 115 g of a viscousyellowish oil (elemental analysis: 12.3% nitrogen).

Air Detrainer 2

A flask was charged with 43 g of polyethylenimine of average molecularmass M_(w) 800 and this initial charge was mixed with 2.7 g of 40%strength aqueous potassium hydroxide solution. The mixture was dewateredon a rotary evaporator under a water pump vacuum at a temperature of upto 120° C. The dry product was then charged under nitrogen at 90° C. toa heatable autoclave provided with a stirrer and was then heated to atemperature of 145° C. As soon as this temperature was reached 93.6 g of1,2-butylene oxide were injected and the reaction mixture was stirred toconstant pressure and then cooled to about 80° C. Removal of the waterfrom the reaction mixture on a rotary evaporator left 137 g of a viscousyellowish oil (elemental analysis: 11.2% nitrogen).

Air Detrainer 3

A heatable autoclave provided with a stirrer was charged under nitrogenwith 43 g of polyethylenimine of average molecular mass M_(w) 3600 inthe form of a 50% strength aqueous solution and, after the autoclave hadbeen closed, this initial charge was heated to a temperature of 120° C.After this temperature was reached 72 g of 1,2-butylene oxide wereinjected and the reaction mixture was stirred to constant pressure andthen cooled to a temperature of 80° C. This gave 115 g of a highlyviscous yellowish oil (elemental analysis: 11.9% nitrogen). This productwas admixed with 5.3 g of 40% strength aqueous potassium hydroxidesolution and the water was then removed under subatmospheric pressure,with the reaction mixture being heated at a temperature of up to 120° C.The dewatered product was then charged under nitrogen into a stirredautoclave, where it was heated to a temperature of 140° C. Then 24.5 gof 1,2-butylene oxide were injected and the reaction mixture was stirredto constant pressure and then cooled to 80° C. This gave 141 g of ayellow viscous oil (elemental analysis: 9.6% nitrogen).

Plasticizer 1

35% strength aqueous solution of a copolymer of

(a) 80% by weight methylpolyethylene glycol methacrylate (prepared byesterifying methylpolyethylene glycol containing 20 ethylene oxide unitswith methacrylic acid) and

(b) 20% by weight methacrylic acid, partially neutralized with sodiumhydroxide solution.

The copolymer had an average molecular mass M_(w) of 25,000. It wasprepared by copolymerizing the monomers in the presence of sodiumhypophosphite in accordance with DE-A-19 653 524.

EXAMPLE 1

A flask equipped with a stirrer was charged with 35 parts of plasticizer1 (based on the solids content of the plasticizer) and this initialcharge was heated to a temperature of 80° C. At this temperature 0.35part of air detrainer 1 (based on solids content) was added withcontinuous stirring and the mixture was stirred until it formed a clearsolution. It was then cooled to room temperature and stored for a periodof 3 months. After this period, the solution was still clear. Neitherclouding nor precipitation was found.

EXAMPLE 2

35 parts of plasticizer 1 (calculated on the basis of the solidscontent) were charged to a stirrer-equipped flask and the contents ofthe flask were heated to a temperature of 80° C. As soon as thistemperature was reached 0.35 part of an aqueous solution of airdetrainer 2 (calculated on the basis of the solids content) was added,said solution having been prepared beforehand by neutralizing airdetrainer 2 with dilute acetic acid. The result was a clear solutionwhich was cooled to room temperature and stored at room temperature for3 months. Following storage this solution was still clear. Neitherclouding nor any precipitation was found.

EXAMPLE 3

35 parts of plasticizer 1 (calculated on the basis of the solidscontent) were charged to a stirrer-equipped flask and the solution washeated to a temperature of 80° C. At this temperature 0.35 part of airdetrainer 3 (calculated on the basis of the solids content) was added,and the mixture was stirred at a temperature of 80° C. for about 90minutes. The result was a clear solution which was cooled to roomtemperature and stored at this temperature for 3 months. Even after3-month storage the solution was clear. No clouding nor precipitationwas found.

EXAMPLES 4-8

Air detrainers 1 to 3 were tested in a concrete mixture for their actionas air pore reducers. The investigations were conducted by the procedureindicated above in accordance with DIN 1048. For Examples 4 to 8 theamount of plasticizer 1 (calculated as 100%) used in each case was0.24%, based on the amount of cement employed. The ratio of water tocement was 0.45 in all cases. The air detrainers used in the examples,and the air pore content of the concrete mixture, are reported in Table1.

TABLE 1 Ex- Air detrai- Amount of air detrai- am- ner ner [%], based onAir pore content ple No. plasticizer 1 [% by volume] 4 2 0.86 4.2 5 21.40 3.2 6 1 0.86 3.8 7 1 1.40 3.2 8 3 1.40 4.2

EXAMPLE 9

In this example different amounts of air detrainer 1 were used relativeto plasticizer 1, and the air pore content was measured in each case.The amounts employed in each case and the results obtained with them arereported in Table 2. As can be seen from that table an increase in theamount of air detrainer added reduces the air pore content in theconcrete. This test was carried out using Heidelberger Zement CEMI 32.5R.

Grading Curve: B 16 Mixing Ratio: 1:5.56

Cement: 2475 g.

All of the investigations reported in Table 2 were carried out using0.26% of plasticizer 1 (calculated as 100%), based on the amount ofcement used. The water:cement ratio was 0.47 in all cases. The amountsof air detrainer, based on the amount of plasticizer employed,calculated as 100% in each case, the air pore content, and the slump arereported in Table 2.

TABLE 2 Air detrainer 1 [%], based Air pore Ex. on plasticizer 1(calcula- content in % Slump in cm 9 ted as 100% in each case) by volumeafter (minutes)  1 30 60 90 120 a) 1.40 2.0 50 39 33 30  28 b) 1.10 2.255 42 35 32  30 c) 0.86 3.8 58 45 35 33  30

EXAMPLE 10

Example 9 was repeated with the changes shown in Table 3. In this case,the results reported in Table 3 were obtained. Whereas the mixture ofair detrainer 1 and plasticizer 1 gave a clear solution which was stableon storage, the mixture of plasticizer 1 with commercially customaryphosphate as air detrainer was cloudy and separated after 48 hours.

Mixtures of plasticizer and antifoam which separate after only a shorttime are unsuitable for use as a cement additive.

TABLE 3 [%] Air detrain- er, based on plasticizer Compressive [%]Plasticizer (calculated as Slump (cm) after strength 1, based on 100% ineach Air pore content (minutes) [N/mm²] after cement case) [% by volume]1 30 60 90 120 1 day 28 days Example 10 0.26 1.0 air detrain- 3.0 58 4535 33 30 30 56 er 1 Comparative 0.26 1.0 commercially 3.0 55 42 35 33 3029 54 Example 2 customary air detrainer (phos- phate)

We claim:
 1. A mixture, comprising: at least one polycarboxylate-basedplasticizer and, as an air detrainer, butoxylated polyalkylenepolyaminesor salts thereof mixed with a mineral building material comprisingcement.
 2. A mixture as claimed in claim 1, which comprises butoxylatedpolyethylenimines or their salts as air detrainers.
 3. A mixture asclaimed in claim 1, which comprises, as air detrainers, the reactionproducts prepared by butoxylating polyethylenimines having molecularweights_ranging from 200 to 5000 with from 0.1 to 10 mol of butyleneoxide per mole of ethylenimine units in the polyethylenimine, or saltsof these products.
 4. A mixture as claimed in claim 1, which comprises,as air detrainers, the reaction products prepared by butoxylatingpolyethylenimines having molecular weights ranging from 400 to 3000 withfrom 0.3 to 5 mol of butylene oxide per mole of ethylenimine units inthe polyethylenimine, or salts of these products.
 5. A mixture asclaimed in claim 1, which comprises, as air detrainers, the reactionproducts prepared by butoxylating polyethylenimines having molecularweights ranging from 600 to 2000 with from 0.8 to 2 mol of butyleneoxide per mole of ethylenimine units in the polyethylenimine, or saltsof these products.
 6. An aqueous solution comprising a mixture of (a) awater-soluble copolymer containing from 98 to 2% by weight of units ofesters of formula (I)

574/98 KS/mm 17.09.1998 in which R¹ and R² are identical or differentand are H or CH₃, A is an alkylene group with 2 to 4 carbon atoms, R³ isH or C₁-C₂₂-alkyl, and n is from 1 to 300, and from 2 to 98% by weightof units of acrylic acid, methacrylic acid, their alkali metal salts andammonium salts, and mixtures thereof, and (b) butoxylatedpolyalkylenepolyamines or their water-soluble salts, said mixturecontaining from 0.3 to 30 parts by weight of component (b) per 100 partsby weight of component (a) and the concentration of component (a) in theaqueous solution being from 5 to 80% by weight.
 7. The aqueous solutionas claimed in claim 6, which comprises water-soluble butoxylatedpolyethylenimines or salts thereof as component (b).
 8. The aqueoussolution as claimed in claim 6, which comprises, as component (b), thereaction products prepared by butoxylating polyethylenimines havingmolecular weights ranging from 200 to 5000 with from 0.1 to 10 mol ofbutylene oxide per mole of ethylenimine units in the polyethylenimine,or salts of these products.
 9. The aqueous solution as claimed in claim8, which comprises, as component (b), the reaction products prepared bybutoxylating polyethylenimines having molecular weights ranging from 400to 3000 with from 0.3 to 5 mol of butylene oxide per mole ofethylenimine units in the polyethylenimine, or salts of these products.10. A mixture as claimed in claim 9, which comprises, as component (b),the reaction products prepared by butoxylating polyethylenimines havingmolecular weights ranging from 600 to 2000 with from 0.8 to 2 mol ofbutylene oxide per mole of ethylenimine units in the polyethylenimine,or salts of these products.
 11. A mixture as claimed in claim 1, whereinthe polyalkylenepolyamine of the butoxylated polyalkylenepolyamine isdiethylenetriamine, triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine, 3-(2-aminoethyl)aminopropylamine,2-(diethylamino)ethylamine, 3-(dimethylamino)propylamine,dimethyldipropylenetriamine, 4-aminoethyl-1,8-octanediamine,3-(diethylamino)propylamine, N,N-diethyl-1,4-pentanediamine,dipropylenetriamine, bis(hexamethylene)triamine,N,N-bis(aminopropyl)methylamine, N,N-bis(aminopropyl)ethylamine,N,N-bis(aminopropyl)hexylamine, N,N-bis(aminopropyl)octylamine,N,N-dimethyldipropylenetriamine, N,N-bis(3-dimethylaminopropyl)amine,N-(aminoethyl)butylenediamine, N-(aminopropyl)butylenediamine,bis(aminopropyl)butylenediamine and polyethylenimine.
 12. A mixture asclaimed in claim 1, wherein the polycarboxylates are homopolymers orcopolymers of acrylic acid, methacrylic acid, copolymers of styrene andmaleic anhydride, copolymers of isobutene and maleic anhydride andcopolymers of diisobutene and maleic anhydride.